1. Field of The Invention
The present invention relates to apparatus, methods and assembly systems for utilizing various types of pile and grouting members to provide a special patterning and array of such members for reduced soil liquefaction in the event of earthquake or other seismic disturbance.
2. Background Information
Although no references were found specifically relating to the vast improvements that the present invention discloses and teaches in this technology; some of the references which disclose aspects of the general technology in an experimental or theoretic sense, include United States Patents to Ringsten, U.S. Pat. No. 4,832,533; Taki, U.S. Pat. No. 5,118,223; Asayama, U.S. Pat. No. 3,975,917; Sato, U.S. Pat. No. 4,707,956; Spanovich, U.S. Pat. No. 3,464,215; and Turzillo, U.S. Pat. No. 3,886,754, and published references including Finn et al., xe2x80x9cLiquefaction in Silty Soils: Design and Analysis,xe2x80x9d ASCE, GSP 44, October, 1994, pp. 51-78; Yourman et al., xe2x80x9cQuality Control of Stone Columns in Variable Soils,xe2x80x9d ASCE Geotechnical Special Publication n. 90, pp.96-110; Liu and Dobry, xe2x80x9cSeismic Response of Shallow Foundation on Liquefiable Sand,xe2x80x9d ASCE, Journal GandGE, June, 1997, pp. 557-567; Galsworthy and El Naggar, xe2x80x9cAnalysis of R/C Chimneys with Soil-Structure Interaction,xe2x80x9d ASCE, GSP 70, October, 1997, pp 23-35; Han and Cathro, xe2x80x9cSeismic Behavior of Tall Buildings Supported On pile Foundations,xe2x80x9d ASCE, GSP 70, October, 1997, pp. 36-51; Kagawa et al., xe2x80x9cSoil-Structure-Pile Interaction in Liquefying Sand From Large-Scale Shaking-Table Tests and Centrifuge Tenst,xe2x80x9d ASCE, GSP 70, October, 1997, pp. 69-84; Kaynia, xe2x80x9cEarthquake Induced Forces in Piles in Layered Soil Media,xe2x80x9d ASCE, GSP 70, October, 1997, pp. 85-95; Ivanetich et al., xe2x80x9cCompaction Grout: A Case History of Seismic Retrofit,xe2x80x9d ASCE, Proceedings of the Geo Denver Conference, August, 2000, pp. 83-93; Desai, xe2x80x9cDCS Constitutive and Computer Models for Soil-Structure and Liquefaction Analysis,xe2x80x9d ASCE Geotechnical Special Publication no. 110, pp. 99-116; Davis and Berrill, xe2x80x9cPore Pressure and Dissipated Energy in Earthquakes Field Verification,xe2x80x9d ASCE Journal GandGE, March, 2001, pp. 269-274; Ashford et al., xe2x80x9cComparison of Deep Foundation Performance in Improved and Non-Improved Ground Using Blast-Induced Liquefaction,xe2x80x9d ASCE Geotechnical Special Publication no. 107, pp. 20-34; Bonita et al., xe2x80x9cIn Situ Liquefaction Evaluation Using a Vibrating Penetrometer,xe2x80x9d ASCE Geotechnical Special Publication no. 107, pp. 191-206; Helwany et al., xe2x80x9cSeismic Analysis of Segmental Retaining Walls, I: Model Verification,xe2x80x9d ASCE JGandG, September, 2001, pp. 741-749; and Tebesh and Paulos, xe2x80x9cPseudostatic Approach for Seismic Analysis of Single Piles,xe2x80x9d ASCE JGandG, September, 2001, pp. 757-765. Perhaps the most important place for publication of earthquake and related technology articles and other information has been considered to be the Journal of Geotechnical and Environmental Engineering, a publication of the ASCE.
The Ringesten ""533 patent reference discloses a process having as it principal teaching the removal of some of the soil below the foundation of a structure and replacing the soil with a xe2x80x98lighter materialxe2x80x99 such as a foamed plastic or such matter as hollow plastic balls; to theoretically provide a soil layer which will distribute the loads from the structure foundations over a broader and deeper soil layer where support will be adequate while at the same time providing some buoyancy to the structure. Although drawings are disclosed in Ringesten which appear to result in an array having some similarity in relation to the present invention; the drawings, in fact, illustrate xe2x80x98drill casingsxe2x80x99 which, in accordance with Ringesten, are subsequently removed when the xe2x80x98light materialxe2x80x99 is being placed.
The Taki ""223 reference discloses an insitu process to form columns by a xe2x80x98soil mixingxe2x80x99 process. It is disclosed in this regard that when the soil is not amenable to jet grouting, that the Taki process may be utilized. Large auger shaped drills are bored into the soil. What appears to look like xe2x80x98augersxe2x80x99 are, in fact, xe2x80x98half augerxe2x80x99 sections which act as mixers by alternately lifting and dropping the soil around the blades. While this is going on, cement grout is injected to mix with the soil, as is also the case in xe2x80x98jet grouting.xe2x80x99 The Taki process is, however, useable with a great many more types of soil than is jet grouting. In the technology, however, it is important to note that neither jet grouting nor soil mixing is really grouting, as applied in the present invention, at all.
Asayama ""917 describes a process which involves placement of piles which have a horizontally fluted exterior profile. It has little connection to the present invention.
The Sato ""956 reference relates to the installation of pile elements connected to a foundation in which movement of the top part of the pile is insulated from the soil directly under the foundation, with the deeper section of the pile carrying support down to deep soil strata. This invention appears to embrace the theory about decreasing the damage from earthquake shock, which says that the soil close under the foundation of a structure should not be compacted. However, this theory is debated and now discounted by most earthquake design engineers. Whether such support, disclosed in Sato, should be utilized, or designed in, is probably a site specific decision involving the types of soil encountered, their density, and the layering present in the formation. The Sato invention has little comparison to the broadly applicable array, and support superiority, of the present invention.
The Spanovich ""215 Patent concerns a method of filling voids while preventing cement grout from escaping endlessly into such voids. Spanovich applies almost exclusively to voids in rock although it could possible apply to very stiff soils which act, or have similar properties, much like rock. This invention has almost no connection with settlement or damage due to liquefaction of soil; and, therefore, does not reasonably relate to the structural or functional purposes of the present invention.
Lin ""736 discloses the construction of pile which has larger diameter areas where the soil of a site is soft and smaller diameter areas where the soil is dense. As disclosed, the horizontally fluted exterior profile, structurally, can assist in support of foundation loads in some soils. Lin teaches that additional support can be created by making the bottom section a xe2x80x98belledxe2x80x99 section.
The Takahashi ""316 patent reference describes what is known in the geotechnical field as xe2x80x98lense grouting.xe2x80x99 As disclosed and illustrated, a cement slurry grout is pumped into loose soil for the purpose of xe2x80x98fracturingxe2x80x99 such soil. Because soil is usually laid down in horizontal layers, the xe2x80x98fracturesxe2x80x99 are usually horizontal along the weak zones. This process leaves a web of cement grout channels, or xe2x80x98lensesxe2x80x99; hence the derivation of its name. The soil on site, exposed to such a process, is not materially changed. Lense grouting is the opposite, conceptually, from compaction grouting, utilized in the present invention, where the bulk of the soil on site is densified. The creation of the lenses can be made somewhat more uniform by starting the grout flow into a hole at a high rate to create a lense; and, then, slowing the rate to expand the lense in thickness. It is possible that the stronger soil mass with its irregular web of lenses could deflect earthquake shock waves in some random fashion, but it would not lend itself to predictability. The Takahashi process appears unrelated to the compaction pile concepts, utilization and configurational positioning and arrays of the present invention.
The Turzillo ""754 patent reference discloses a process used to hold a drilled hole open while cement grout is pumped in, for the purpose of creating an insitu pile. The process is widely utilized today, conventionally, to install mini-piles. The resulting pile, however, in and of itself, has no specific characteristics and the surrounding soil on site is not compacted or densified, as is the case of employing the teaching of the present invention.
In the Finn publication, the analysis disclosed predicates itself on the fact that piles situated in a sandy soil dramatically reduce the liquefaction potential. A model set forth regarding dam failure showed that the most stressed zone was upstream of the spillway and below the bottom of the dam fill. Piles were driven into that weak zone in a test case at the Sardis Dam in British Columbia. Post treatment soil tests indicated that this pile reinforcing in the express critical, weak zone prevented liquefaction and increased the apparent factor of safety of the dam some threefold. However, in this study, soils were not compacted, as utilized in the present invention.
The Yourman publication discloses a study where the density of the soil was used to attempt to measure the consistency with which stone column data would replicate. The correlation was not found to be good. There was no discussion relating to the present invention, though stone columns are illustrated as laid out in some spaced pattern, in a design test section.
The Liu and Dobry publication discloses experiments conducted utilizing a viscous fluid (ethylene glycol) to simulate increased gravity (as with a centrifuge). The experimental results were correlated with actual results from several earthquakes and with centrifuge data. The intention of the publication appears to be based on providing another possible method of detecting before and after differences utilizing support methods. One of the publication""s diagrams (FIGS. 4(a) and 4(b)) discloses an area where pore pressure transducers and accelerometers are installed at desired locations in the xe2x80x98modelxe2x80x99 used, at appropriate times during deposition. It is intended to illustrate, after the whole thickness of the sand has been placed, that a vibrating tube, 6.4 mm. in diameter (0.5 m. prototype), is inserted into the sand at 19 locations over a circular area having a diameter about 60% larger than the footing diameter (identified as xe2x80x9cBxe2x80x9d in the diagram) so as to compact the sand under and around the assumed footing location. This is very different in structure, patterning and functional scope and purpose than that of the present Pile Array Assembly System of the present invention.
The Galsworthy and El Naggar publication analyzes the effects of foundation types on the resistence of tall chimneys to earthquake damage. The types of foundations examined included those on piles extending to rock, those on friction piles and those on floating mats. The finding was that the more flexible the foundation, the lower the magnitude of damage to the chimney. In this publication one of the diagrams presented (FIG. 1a) illustrates a conventional end-Bearing Pile Foundation, having no similarity to the structural novelties of the present invention.
The Han and Cathro publication addresses seismic behavior of tall buildings supported on conventional pile foundations; and specifically concerns the analysis of a 20 story building on a square foundation. Two options of pile arrangements are disclosed and assumed to be friction piles as is customary in the technology, placed using 4xc3x974 and 5xc3x975 spacing options. The piles used are disclosed as being pre-cast concrete with a diameter of 0.4 m., installed by driving each a depth of 24 m. The soil interaction is said to sizably reduce the cycle of vibration and to transfer smaller strains into the structure. This is said to result in less movement at higher frequency.
The Kagawa publication addresses soil-structure-pile interaction in liquefying sand from large-scale shaking-table and centrifuge tests; and suggests that the main damage of a pile-supported tall structure occurs where the piles are attached at the top portion thereof in the foundation, and at the bottom portion thereof where founded on rock or on stiff soils. The publication indicates that there is little stress or damage to the middle section of respective piles.
The Kaynia work addresses earthquake induced forces in piles in layered soil media, and sets forth an analysis of pile interactive forces inlayers of different soil, indicating that major damage occurs where the soil is weak. No differentiation is made. This appears to be confirmed in many studies made regarding the Loma Prieta damage. A conventional pile-soil-structure system is illustrated (FIG. 1) in this publication.
The Ivanetich publication of August, 2000 is entitled: xe2x80x9cCompaction Grout: A Case History of Seismic Retrofit.xe2x80x9d The publication describes an extensive program of soil grouting beneath the foundations of a bridge in California, where the intention or functional purpose of the approach was soil stability and support with respect to improvement of soil of the type which tends to liquefy under the shock forces of an earthquake. The type of improvement disclosed in this publication appears to exploit the well known features of soil compaction in the technology by compaction grouting; i.e., the soil being densified insitu to resist liquefaction simply by creating a more dense soil. The results reported were verified by before-and-after soil density readings. The measurement methods employed involved obtaining standard penetration test (SPT) and cone penetration (CPT) readings in the area where the grouting was carried out and baseline data being obtained on the soil density in the zone where settlement was considered to be most likely to occur. Compaction grout columns of injections were then placed utilizing a prescribed pattern and depth of injection. Examples of this compaction grouting layout, regarding two (2) Pier structure sites, are set forth at FIG. 2 of the Ivanetich publication, at page 87. The layout appears to utilize grouting locations for parallel and square-rectangular-grid arrangement of Primary Grout Locations, Secondary Grout Locations and Angled Grout Locations; as shown by symbol to represent an 11xc3x9711xe2x80x2 Sq. Pattern and a 15xe2x80x2xc3x9715xe2x80x2 Sq. Pattern. After the grouting, a selected number of SPT and CPT tests were run to measure the soil density after compaction; being located between the points of grout injection. During grouting in Ivanetich, low mobility grout was utilized rather than true compaction grout. This approach, it is submitted, might give a satisfactory result if soil densification was the only result required. However, such grout might well flare off in the soil and not result in true compaction pile shapes.
The results from Ivanetich indicated an overall improvement in the soil properties as measured by the SPT tests. However, in individual locations, the improvement ranged from a dramatic two (2) times denser to no density improvement at all. As one would expect in this technology, post treatment CPT data paralleled the SPT data. Ivanetich concludes that the average improvement is roughly equivalent to preventing damage by an earthquake measuring xe2x80x98onexe2x80x99 number greater on the Richter scale; i.e., from a Richter 5 to a 6, or 6 to a 7. The Ivanetich work was apparently targeted to mitigate the shock of a Richter 8 earthquake. However, there is no way of telling whether there are meaningful effects from the specific work done. Ivanetich concludes that it may be reasonable to carry out the programs suggested even at the high cost of such work because the risks of not doing it are so great. However, the plausibility of the Ivanetich work based on its inconsistent results would not appear to be justified in relation to the realistic eventuality of the earthquake disaster anticipated in Ivanetich.
Davis and Berrill discuss the relationship of pore pressure increases (p) to dissipated energy (D); and set forth what they reference as a so-called D-p theory. They correlate real data from several earthquakes in the U.S. and Japan to develop correlation constants.
Bonita et al. Deals with soil liquefaction and describes a set of parameters relating to specific sites where ground improvements had been made. There was no implication or recognizance of the phenomenon of seismic shock wave reduction.
Tabesh and Poulos sets forth schematically a conventional arrangement of piles in FIG. 6 of their presentation regarding a pseudostatic approach for seismic analysis of single piles.
Predictive models have advanced rapidly in the last decade. There are presently ways of translating the ground effects of an earthquake of any given magnitude into ground reaction and performance data. This is being done to begin to gauge the effects on building foundations. It is not clear, however, in the prior art, what the best methods are of counteracting building destruction. Modeling of a small scale utilizing a centrifuge has begun in the recent past; and as this approach develops, it should provide a means of experimenting which should prove more effective than any other method in testing the protective earthquake technology structures.
However, at present, none of the patent or publication references found in the prior art specifically illustrate or disclose the angular pile array assembly system for reduced soil liquefaction of the present invention. Nor is the present invention obvious, in this or closely related technologies, in view of any of the prior art references listed. In addition, all of the relevant prior art heretofore known suffer from a number of disadvantages.
A significant shortcoming in the prior art is that it does not offer a system, adequately responsive to seismic disturbances, which appears to, both, provide adequate ground support against liquefaction and also provide the soil with a greater magnitude of density to resist liquefaction.
An additional problem in the prior art is that a suitable protective array of grouting elements positionally placed in the ground soil in relation to a building structure, has not previously been available; nor have the various grouting and pile structures conventionally available been positionally deployed in ground soil adjacent to buildings and other structures to obtain the greatest advantage.
The prior art has further suffered in not providing a ground soil structural support system which adequately takes advantage of the dynamic seismic principles relating to shock wave dissemination, reflection/deflection and dissipation of energy waves underground, during seismic disturbances or earthquakes.
Yet a further problem or defect in the prior art has been the absence of adequate pile, grouting or compaction grouting support for providing better ground support protection against the seismic propagation of lateral or horizontal energy waves, as this relates to the stability of ground soil adjacent or proximate to building, bridge, wharf, pier, highway or roadway structures.
These and other defects, problems and shortcomings of the prior art technology, structurally and functionally, will become apparent in reviewing the remainder of the present specification, claims and drawings.
Accordingly, it is an object of the present invention to provide a novel pile array system which will significantly reduce or lessen seismic shock on the footing of a structure from earthquakes or other occurrences and the related damages to ground structures and buildings.
It is a further object of the present invention to provide a pile array system which will reduce soil liquefaction both by virtue of a novelly positioned structural array support to dissipate seismic shock waves and by the added ground density afforded to a ground site by the installation of such an array system; or, stating this another way, by the invention""s use of compaction piles, grouting or other pile or column menas placed in a deflecting array, while densifying the soil at the same time.
It is yet a further object of the present invention to provide a pile array system which is versatile and adoptable to utilizing several significant types of grouting, piles, and stone columns; and which can be used in interaction or association with other soil liquefaction reduction methods.
It is a further object to provide a pile array assembly which can be utilized under a ground structure""s foundation or footing, without necessarily being in direct contact with such a structure.
It is a further object to provide a pile array system which will have the capacity of reducing a seismic shock wave by two orders of magnitude; example, from richter scale 7 to 5.
Yet a further object is to provide a pile array system which will best interrupt, deflect and redistribute seismic shock waves so as to significantly lower the intensity of shock wave and reduce or prevent settlement of building and ground structure foundations.
It is yet a further object to provide further enhancements to a soil installation site by virtue of the installation process of the present invention, especially with regard to tolerances and pile member location, adjacent distance to footing and consolidation of adjacent soil; drilling depth in relation to adjacent bedrock or dense soil layers, and pile positioning and placement; and the utilization of arced or arched positional support array configurations to maximize seismic wave deflection and ground site densification.
It will, therefore, be understood that substantial and distinguishable structural and functional advantages are realized in the present invention over the prior art teachings; and that the present invention""s novel placement, configuration and array structure; diverse utility in serving at least two or more seismically significant functions contemporaneously; and broad functional applications serve as important bases of novelty and distinction in this regard.
The foregoing and other objects of the invention can be achieved with the present invention, device, assembly and system which is a pile array assembly system for use in interaction with a ground soil site and footing adjacent to and supporting a ground surface structure of building for reduced soil liquefaction and providing greater ground stability in the event of an earthquake or other seismic disturbance.
The invention is provided with a first array subassembly having a plurality or number of pile units. Each of the pile units have first and second ends and a lengthwise lateral wall extending between these two ends. Each of the piles is positioned and placed, in interaction with a ground soil site, at specific ground entry points so as to extend and slope at a theta-1 angle in relation to an imaginary vertical axis defined and extending from each of the respective entry points. By positioning in this manner, the first ends of each of the respective pile units are generally positioned and placed so as to define, when imaginary interconnecting periphery lines are attached thereto, a first perimeter. The second ends of each of the respective pile units are positioned and placed so as to define, when imaginary interconnecting periphery lines are attached thereto, a second perimeter which is greater in dimensional magnitude than that of the first perimeter. A first positional axis is defined between the first and second ends extending between the first perimeter and the second perimeter as to each of the respective pile units of the first array subassembly.
The invention is further provided with a second array subassembly having a number of pile units. Each of the pile units have first and second ends and a lengthwise lateral wall extending between these two ends. Each of the piles is positioned and placed, in interaction with a ground soil site, at specific ground entry points so as to extend and slope at a theta-2 angle in relation to an imaginary vertical axis defined and extending from each of the respective entry points. By positioning in this manner, the first ends of each of the respective pile units are generally positioned and placed so as to define, when imaginary interconnecting periphery lines are attached thereto, a third perimeter. The second ends of each of the respective pile units are positioned and placed so as to define, when imaginary interconnecting periphery lines are attached thereto, a fourth perimeter which is greater in dimensional magnitude than that of the third perimeter. A first positional axis is defined between the first and second ends extending between the third perimeter and the fourth perimeter as to each of the respective pile units of the second array subassembly.
The invention is further provided with a third array subassembly having a number of pile units. Each of the pile units have first and second ends and a lengthwise lateral wall extending between these two ends. Each of the piles is positioned and placed, in interaction with a ground soil site, at specific ground entry points so as to extend and slope at a theta-3 angle in relation to an imaginary vertical axis defined and extending from each of the respective entry points. By positioning in this manner, the first ends of each of the respective pile units are generally positioned and placed so as to define, when imaginary interconnecting periphery lines are attached thereto, a fifth perimeter. The second ends of each of the respective pile units are positioned and placed so as to define, when imaginary interconnecting periphery lines are attached thereto, a sixth perimeter which is greater in dimensional magnitude than that of the fifth perimeter. A first positional axis is defined between the first and second ends extending between the fifth perimeter and the sixth perimeter as to each of the respective pile units of the third array subassembly.
The present invention further comprises a fourth array subassembly having a number of pile units, with each of the piles having first and second ends and a lengthwise lateral wall extending between the two ends. Each of the pile units are positioned and placed in interaction with a ground soil site at specific ground entry points generally proximal and along the fifth perimeter at points between the respective pile units of the third array so as to extend at a gamma angle in relation to an imaginary vertical axis extending from each of the respective entry points, so that the first ends of each of the respective pile units are generally positioned and placed generally proximal and along the fifth perimeter and the second ends of each of the respective pile units are generally positioned and placed so as to define, when imaginary interconnecting periphery lines are attached thereto, a seventh perimeter which is of less dimensional magnitude than that of the third perimeter.